In recent years, high brightness LEDs which generate a strong light and a large amount of heat have been commercialized and widely used for general purpose illumination. Japanese Patent Application Laid-Open No. 2005-272697 discloses that a hinderdamine light stabilizer is added to a phenyl silicone resin to provide an encapsulating material having good heat resistance, stability in light resistance and weather resistance. The silicone resin composition has good light resistance, heat discoloration resistance and impact resistance, but the effect of the light stabilizer decreases in a long period of use, the phenyl group is decomposed to cause discoloration of the resin, and the siloxane bond is broken to degrade the resin.
Japanese National Phase Publication No. 2009-527622 discloses a silicone resin composition comprising a phenyl group-containing organopolysiloxane and a hydrogendiorganosiloxy-terminated oligodiphenylsiloxane. However, when the silicone resin composition is used in a high brightness LED package which generates a strong light and a large amount of heat, cracks occur at the edge of an LED package or the base of a lead frame. Particularly, its adhesiveness to silver is worse to cause peeling at the interface between an LED package and a silver frame.